The objective of this research is to characterize the molecular structure and stabilizing interactions of the myelin sheath by coordinated x-ray diffraction, thin-section and freeze-fracture electron microscopy, and chemical analysis. Measurements will be made on intact myelin and on purified myelin membranes and lipids isolated from the central and peripheral nervous systems. The problems to be explored include: The mechanism of compaction and vesiculation of myelin membranes by calcium and local anesthetics; the kinetics of transformation by specific ion binding and dehydration; the structure of transitional states trapped by quick freezing; the nature of intermembrane stabilizing forces from study of perturbed states. This information will help to characterize the physical processes of myelin breakdown in disease such as multiple sclerosis. Study of disease states, in turn, will lead to a better understanding of control processes in normal membrane interactions.